1. Field of the Invention
The present invention relates to portable telephone sets, and more particularly to a portable telephone set suitable for a global system for mobile communication (GSM).
Recently, it has been considered in Japan to employ, as a communication system using portable telephone sets, the GSM which has been employed in Europe. The GSM does not require registration of a telephone number for each portable telephone set. Each individual (subscriber) is assigned to a subscriber identity module in which information concerning the subscriber is stored. If the subscriber exchanges the old portable telephone set by a new one, the subscriber identity module is detached from the old telephone set and is then inserted into the new one. If the rent portable telephone set is used, the subscriber inserts the own subscriber identity module into the set. Thus, the new or rent portable telephone set can be used as the subscriber own portable telephone set.
It has been considered that the subscriber identity module is realized by a compact subscriber identity card in which an integrated circuit including a memory is built. Such a card has a size of, for instance, 25 mm.times.15 mm.
The portable telephone set has been required to be thin and have a structure which enables the subscriber identity card to be easily detached therefrom.
There is another card which can be inserted into the portable telephone set. Such a card stores information important to the subscriber, such as subscriber identity information and accounting information. It is not desired to easily detach, from the portable telephone set, the information cards suitable for the portable telephone set as described above in terms of privacy protection. The portable telephone set is required to satisfy the above.
In the present specification, the cards to be attached to the portable telephone sets are referred to as portable telephone information cards. The portable telephone information cards include the above subscriber identity card, and another card which stores information other than the subscriber identity information.
2. Description of the Related Art
FIGS. 1A and 1B are diagrams of a portable telephone set 10 for the GSM disclosed in Japanese Laid-Open Patent Application No. 8-265404. A battery pack 11 can be attached to the back surface of the portable telephone set 10. A card loading mechanism 12 is provided in a bottom surface portion of a battery pack mount portion 13 provided to the back surface of the portable telephone set 10, that is, the back surface of the mounted battery pack 11. The battery pack mount portion 13 has a bottom plate 14, in which a rectangular opening 15 is formed.
The subscriber identity card loading mechanism 12 is mainly composed of a housing 20 and a holder 21. The housing 20 is fixed to the inside of the portable telephone set 10, and faces the opening 15. The holder 21 is joined to the housing by a hinge.
A subscriber identity card 22 can be mounted as follows. The holder 21 is rotated and set upright. Then, the subscriber identity card 22 is inserted into the holder 21, which is then depressed and rotated. Thus, the card 22 passes through the opening 15 and is engaged with the housing 20.
The subscriber identity card 22 can be taken out by the reverse operation. It should be noted that the subscriber identity card 22 which is mounted cannot be taken out unless the battery pack 11 is taken out.
The above portable telephone set 10 has the following problems.
The battery pack mount portion 13 located in the back surface of the portable telephone set 10 includes a slight recess. A circuit board, a tenkey and other components are tightly provided in a portion 16 opposite to the battery pack mount portion 13. Thus, no space is available in which a new mechanism is provided. The card loading mechanism 12 is provided in the above portion 16, and thus has an increased thickness t1. Hence, the thickness t3 of the portable telephone set 10 is equal to the sum of the thickness t2 necessary to provide the circuit board, the tenkey and other components and the thickness t1 of the card loading mechanism 12. The thickness t3 prevents down-sizing of the portable telephone set 10.
The holder 21 cannot be detached from the housing 20. Hence, it is necessary to take the portable telephone 10 by hand in order to take out the subscriber identity card 22 from the holder 21 and insert the subscriber identity card 22 into the holder 21. The above is troublesome. Further, the card loading mechanism 12 has a complex structure.
A detection switch detects the holder 21 even when the holder 21 having no card is mounted. Hence, if the subscriber dials with no card inserted into the holder 21, the portable telephone set 10 starts a corresponding calling procedure although it is not completed.